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Rosalind Elsie Franklin worked with X-ray crystallography at King's College London, UK, and she helped determine the helical structure of DNA in the early 1950s. Franklin's research helped establish molecular genetics, a field that investigates how heredity works on the molecular level. The discovery of the structure of DNA also made future research possible into the molecular basis of embryonic development, genetic disorders, and gene manipulation.

Golden Rice was engineered from normal rice by Ingo Potrykus and Peter Beyer in the 1990s to help improve human health. Golden Rice has an engineered multi-gene biochemical pathway in its genome. This pathway produces beta-carotene, a molecule that becomes vitamin A when metabolized by humans. Ingo Potrykus worked at the Swiss Federal Institute of Technology in Zurich, Switzerland, and Peter Beyer worked at University of Freiburg, in Freiburg, Germany. The US Rockefeller Foundation supported their collaboration.

The Sex-determining Region Y (Sry in mammals but SRY in humans) is a gene found on Y chromosomes that leads to the development of male phenotypes, such as testes. The Sry gene, located on the short branch of the Y chromosome, initiates male embryonic development in the XY sex determination system. The Sry gene follows the central dogma of molecular biology; the DNA encoding the gene is transcribed into messenger RNA, which then produces a single Sry protein.

Walter Stanborough Sutton studied grasshoppers and connected the phenomena of meiosis, segregation, and independent assortment with the chromosomal theory of inheritance in the early twentieth century in the US. Sutton researched chromosomes, then called inheritance mechanisms. He confirmed a theory of Wilhelm Roux, who studied embryos in Breslau, Germany, in the late 1880s, who had argued that chromosomes and heredity were linked. Theodor Boveri, working in Munich, Germany, independently reached similar conclusions about heredity as Sutton.

The Cell in Development and Inheritance, by Edmund Beecher Wilson, provided a textbook introduction to cell biology for generations of biologists in the twentieth century. In his book, Wilson integrated information about development, inheritance, chromosomes, organelles, and the structure and functions of cells. First published in 1896, the book started with 371 pages, grew to 483 pages in the second edition that appeared in 1900, and expanded to 1,231 pages by the third and final edition in 1925.

By 2011, researchers in the US had established that non-invasive blood tests can accurately determine the gender of a human fetus as early as seven weeks after fertilization. Experts predicted that this ability may encourage the use of prenatal sex screening tests by women interested to know the gender of their fetuses. As more people begin to use non-invasive blood tests that accurately determine the sex of the fetus at 7 weeks, many ethical questions pertaining to regulation, the consequences of gender-imbalanced societies, and altered meanings of the parent-child relationship.

Alfred Henry Sturtevant studied heredity in fruit flies in the US throughout the twentieth century. From 1910 to 1928, Sturtevant worked in Thomas Hunt Morgan’s research lab in New York City, New York. Sturtevant, Morgan, and other researchers established that chromosomes play a role in the inheritance of traits. In 1913, as an undergraduate, Sturtevant created one of the earliest genetic maps of a fruit fly chromosome, which showed the relative positions of genes along the chromosome.

Katharina Dorothea Dalton was a physician in England in the twentieth century who defined premenstrual syndrome (PMS) as a cluster of symptoms suspected to begin one to two weeks before menstruation and disappear upon the onset of a new menstrual cycle. Prior to Dalton, there was little research on pre-menstrual issues and those that existed linked the problem to excessive water retention or estrogen. Dalton hypothesized that PMS resulted from a deficiency in the hormone progesterone and advocated for hormone replacement therapy to lessen the symptoms of the syndrome.

Thalidomide is a sedative drug introduced to European markets on 1 October 1957 after extensive testing on rodent embryos to ensure its safety. Early laboratory tests in rodent populations showed that pregnant rodents could safely use it, so doctors prescribed Thalidomide to treat morning sickness in pregnant women. However, in humans Thalidomide interfered with embryonic and fetal development in ways not observed in rodent tests.

In the 1973 case of Roe v. Wade, the US Supreme Court ruled that laws banning abortion violated the US Constitution. The Texas abortion laws, articles 1191–1194, and 1196 of the Texas penal code, made abortion illegal and criminalized those who performed or facilitated the procedure. Prior to Roe v. Wade, most states heavily regulated or banned abortions. The US Supreme Court decision in Roe v. Wade secured women's rights to terminate pregnancies for any reasons within the first trimester of pregnancy.

A licensed obstetrician and gynecologist, Pearl Tang worked to improve the health of women and children in Maricopa County, Arizona, during the twentieth and twenty-first centuries. Her work with the Maricopa County Health Department ranged from immunizations to preventing cervical cancer. Tang obtained federal grants and community support to establish various child and maternal health clinics throughout Maricopa County as chief of the Maricopa County Bureau of Maternal and Child Health.

In 2004 Mark Landon and his colleagues in the United States published “Maternal and Perinatal Outcomes Associated with a Trial of Labor after Prior Cesarean Delivery,” which compared the risks of vaginal delivery and cesarean section for delivery of a fetus after a previous cesarean delivery. During a cesarean section, a physician surgically removes a fetus from a pregnant woman through an incision in her abdomen. By the late 1900s, most clinical guidelines viewed attempting a vaginal birth after a previous cesarean delivery as a reasonable option for most women.

In 1942, the United States Supreme Court Case of Skinner v. Oklahoma ruled that states could not legally sterilize those inmates of prisons deemed habitual criminals. Skinner v. Oklahoma was about the case of Jack Skinner, an inmate of the Oklahoma State Penitentiary in McAlester, Oklahoma, who was subject to sterilization under the Oklahoma Habitual Criminal Sterilization Act of 1935. The case, decided on 1 June 1942, determined that state laws were unconstitutional if those laws enabled states to forcibly sterilize inmates deemed to be habitual criminals.

Hermann Joseph Muller studied the effects of x-ray radiation on genetic material in the US during the twentieth century. At that time, scientists had yet to determine the dangers that x-rays presented. In 1927, Muller demonstrated that x-rays, a form of high-energy radiation, can mutate the structure of genetic material. Muller warned others of the dangers of radiation, advising radiologists to protect themselves and their patients from radiation. He also opposed the indiscriminate use of radiation in medical and industrial fields.

A Treatise on the Theory and Practice of Midwifery is a three volume collection of patient accounts that William Smellie published from 1752 to 1764. Smellie, a physician and instructor in obstetrics in Great Britain, published these compilations to share his expertise in reproductive medicine, while also providing his students and colleagues with a source of reference in their own medical practices. Smellie wrote these books to shift obstetrics from a discipline practiced by midwives with limited medical training to one practiced in a medical context by physicians.

Physician researchers Edgar Rey Sanabria and Héctor Martínez-Gómez developed the Kangaroo Mother Program in Bogotá, Colombia, in 1979, as an alternative to conventional incubator treatment for low birth weight infants. As of 2018, low birth weight and its associated complications are the leading causes of infant death, especially in developing and underdeveloped countries where access to technology and skilled healthcare providers is limited. Kangaroo Mother Care is a simple and low cost method for treating low birth weight infants.

All cells that have a nucleus, including plant, animal, fungal cells, and most single-celled protists, also have mitochondria. Mitochondria are particles called organelles found outside the nucleus in a cell's cytoplasm. The main function of mitochondria is to supply energy to the cell, and therefore to the organism. The theory for how mitochondria evolved, proposed by Lynn Margulis in the twentieth century, is that they were once free-living organisms.

Barbara McClintock worked on genetics in corn (maize) plants and spent most of her life conducting research at the Cold Spring Harbor Laboratory in Laurel Hollow, New York. McClintock's research focused on reproduction and mutations in maize, and described the phenomenon of genetic crossover in chromosomes. Through her maize mutation experiments, McClintock observed transposons, or mobile elements of genes within the chromosome, which jump around the genome. McClintock received the Nobel Prize for Physiology or Medicine in 1983 for her research on chromosome transposition.

The Public Broadcasting Station (PBS) documentary Life's Greatest Miracle (abbreviated Miracle, available at http://www.pbs.org/wgbh/nova/miracle/program.html), is arguably one of the most vivid illustrations of the making of new human life. Presented as part of the PBS television series NOVA, Miracle is a little less than an hour long and was first aired 20 November 2001. The program was written and produced by Julia Cort and features images by renowned Swedish photographer Lennart Nilsson.

Paul Kammerer conducted experiments on amphibians and marine animals at the Vivarium, a research institute in Vienna, Austria, in the early twentieth century. Kammerer bred organisms in captivity, and he induced them to develop particular adaptations, which Kammerer claimed the organismss offspring would inherit. Kammerer argued that his results demonstrated the inheritance of acquired characteristics, or Lamarckian inheritance. The Lamarckian theory of inheritance posits that individuals transmit acquired traits to their offspring.

A Treatise on the Theory and Practice of Midwifery is a three volume collection of patient accounts that William Smellie published from 1752 to 1764. Smellie, a physician and instructor in obstetrics in Great Britain, published these compilations to share his expertise in reproductive medicine, while also providing his students and colleagues with a source of reference in their own medical practices. Smellie wrote these books to shift obstetrics from a discipline practiced by midwives with limited medical training to one practiced in a medical context by physicians.

David Michael Rorvik is a science journalist who publicized advancements in the field of reproductive medicine during the late twentieth century. Rorvik wrote magazine articles and books in which he discussed emerging methods and technologies that contributed to the progression of reproductive health, including sex determination, in vitro fertilization, and human cloning. During that time, those topics were controversial and researchers often questioned Rorvik’s work for accuracy.

During the twentieth century in the United States, Alfred Day Hershey studied phages, or viruses that infect bacteria, and experimentally verified that genes were made of deoxyribonucleic acid, or DNA. Genes are molecular, heritable instructions for how an organism develops. When Hershey started to study phages, scientists did not know if phages contained genes, or whether genes were made of DNA or protein. In 1952, Hershey and his research assistant, Martha Chase, conducted phage experiments that convinced scientists that genes were made of DNA.

The Pfeffer Zelle (Pfeffer Cell Apparatus), invented by Wilhelm Pfeffer in 1877, measured the minimum pressure needed to prevent a pure solvent from passing into a solution across a semi-permeable membrane, called osmotic pressure. The apparatus provided Pfeffer with a way to quantitatively measure osmotic pressure. Pfeffer devised the apparatus in the 1870s at the University of Basel in Basel, Switzerland, and he described the Pfeffer Cell Apparatus in his 1877 book Osmotische Untersuchungen: Studien Zur Zellmechanik (Osmotic Investigations: Studies on Cell Mechanics).

In 1951 and 1952, Alfred Hershey and Martha Chase conducted a series of experiments at the Carnegie Institute of Washington in Cold Spring Harbor, New York, that verified genes were made of deoxyribonucleic acid, or DNA. Hershey and Chase performed their experiments, later named the Hershey-Chase experiments, on viruses that infect bacteria, also called bacteriophages. The experiments followed decades of scientists’ skepticism about whether genetic material was composed of protein or DNA.